Rail detector pickup and coil



Oct. 9, 1956 'c, w. MCKEE ET AL 7 2,

RAIL. DETECTOR PICKUP AND c0 1; Filed Nov. 15 1951 2 Sheets-Sheet 1 Cheat w H iie Picfzaiii 1%(11126 Oct. 9, 1956 1. w. MOKEE ET AL 2,766,425

RAIL DETECTOR PICKUP AND COIL Filed Nov. 15 ,[1951 2 Sheets-Sheet 2 detector fissure detector car The alpper coil .serves to. produce United States Patent RAIL DETECTOR PICKUP ANDQCOIL "Chester W. -McKee-and Richard W. "-M'c Kee, Chicago,

-: lll assignors, vby mesne assignments, .a corporation of Idaho .to vZfcfeweld, Inca,

.Thisinvention relates .to a rail detector. pickup and coil. :Ithas been developed primarily for use theTeleand to. replace in part the pickup coil and assembly disclosed in copending application Serial No. 72,382, filed January-24, 1949, which has issued into Patent No. 2,639,316,..dated May 19, 1953.

The pickup coil disclosed in that application consists of a cylindricalspool having an annular channel at right angles to its axis one-sixteenth of an inch from the lower end and a similarannular channel upwardly one-half inch. The spool is one-half inch in diameter and one inch high, and is mounted in a multiple pickup coil assembly by positioning. it in a cylindrical cavity inv a non-conductive block'with ,itsaxis at right angles to the ball-surface. The two channels contain respectively a large number of windings of fine wire, the turns in the-upper channel being reversed in direction to the turns in the l'owerwindings and'bothi being series connected to. eachother with their respective othersleads connected .to ground and the input of =an amplifier. The lowercoil is close to the railand'is principally. responsible for. generating potential signals significant of physical abnormalities inthe railstructure. an offsetting potential signal whenever the pickup coil v.cutslines of .forcedue to vertical movements of the coil with respect to the rail.

The arra ugflmentshownin this copending.application was practical for a car having light magnets and high gain amplifiers. More recently, .applicantsfhave built a car with veryheavy magnets which establish a very-strong field. The. old pickup coilshad. nodifiiculty-in picking upfive toten percent fissures, but the large fissuresiwere missed,.- indicating that the upper. COilzWls canceling the lowercoil when a great change in thel-l-ux field, as bya large fissure, occurred.

One. object of thi invention is to eliminate this difficulty by moving the upper or bucking coil to a point behind the lower coil in the same horizontal plane. By experiment .it was determined that this was superior to moving the upper coil further above the lower coil. The disadvantage of doubling the number of potential signals in traversing a selected flux field was outweighed by the advantage of positioning the two coils at the same distance above the rail, due to the lack of sensitivity of the pen unit.

A second object of this invention is to keep the over-all length of the two coils lying side by side as short as possible, while retaining the feature of non-magnetic cores in the coils. In accomplishing this, applicant adopted an elongated in cross section) core positioned transversely of the rail which has the joint effect of reducing the amount of wire that is merely threading a trailing sustained field where the flux is moving in vertical planes parallel to the length of the rail and of increasing the amount of wire that is moving squarely at right angles to such lines of flux.

Another object of this invention is to eliminate the skipped space between the side-by-side but spaced pickup operator by comparing the action of gauge or field channels with the next adjacent pen, can

2,766,425 Fatented Oct. 9, .1956

coils shown in the copending application. Channel checking of a rail has provedsuccessful. Not only does it enable an operator to more exactly locate the transverse position of. a fissure before hand checking, but a skilled the pens writing the spot shells and flows on the rail ball edges which he cannot clearly see from his seat. A feature of the present invention is the retention of the pickup block, with, how- .ever, the spoolrecesses substantially touching each other and the spools themselves substantially touching each other.

Another object of this invention is to more carefully search the rail ball on the gauge side of center. The most commonplace for fissures to start is beneath that point of a rail ballwhich receives the heaviest wheeling, and that place isslightly to the gauge side of center. A feature of this invention. is the provision of a channel with ,coils that slightly overlaps each adjacent channel so that the smallest internal gap in the continuity of the rail lying at the edges of this important channel will not be missed.

These and such other objects as may hereinafter appear are attained in the. embodiment of the invention shown in the a ccompanying drawings, wherein:

.Fig. 1 is-a side elevation of a pickup carriage illustrating the position of the pickup;

Fig. 2 is a perspective illustration of the pickup block showing in exploded fashion two different types of spool coils ready for mounting in said block;

Fig. 3 is a view taken on the line 33 of Fig. 2;

Fig. 4- is a view taken on the line 44 of Fig. 2;

.Fig. 5 is a view taken on the line 55 of Fig.2;

Fig. 6 is a plan view of the pickup over a rail taken With a schematic wiring diagram illustrating how the coils are. connected to a pen over a tape; and,

.Figs. 7 and 8 areschematic illustrations of a side eleva- .tionand plan view of the line of flux of applicants trailing. sustained field.

Continuing toieferto the drawings, applicants pickup utilizes ninepickup coils or spools varyingin diameter from one-half to three-quarters of an inch. The teaching .ofcopending application Serial No. 72,382, filedlanuary 24, 1949, :as to how to mount such small coilsin exact relationship toieachother in ablock is followed-here. The-numeral It), referring to Fig.1, identifiesa block of non-magnetic and electrically non-conductive material, which is suspended by any suitable means from a plate 12 which in turn .issuspended from frame14 riding on four pairs of. wheels. 16, .18, 2Q) .and.22, these numbersdesign'atingthe near-wheels only. The framelZ is hung by. hangers24 and 26 from a fissure detector car, not shown.

Examing now the pickup block, and referring to Fig. 2, this block has drilled through .it four pairs of holes, 28 and 6t), 30 and 62, 32 and 64, and 34 and 66, and a single hole 36. Referring to Fig. 6, where we are looking downwardly on the block, the position of the block over a 131 pound rail 38 is illustrated. The width of the head of that rail is substantially covered by the pairs of openings, 28, 30, 32 and 34. The diameter of the openings of the holes 28, 3t) and 32 is slightly less than the diameter of the holes 34, and the holes 34 are positioned rearwardly of the transverse alignment of the holes 28, 30 and 32 in order that the longitudinal path of these holes along the rail will overlap the path of the inside edges of the hOles 30 and 32. The bottoms of the holes are closed by a plastic plate 40, see Fig. l, which is screwed to the block 10.

Returning now to Fig. 2, one of applicants spool-type coils in perspective is designated by the numeral 42. This coil, referring also to Figs. 3, 4 and 5, consists of a cylinder or spool of non-conductive material 44 which has had cut in it a deep parallel slot 46, leaving a cap or spacer piece 48 held to the main spool by a land 50 which is rectangular in cross section, see Fig. 5. Around this land is wound several thousand turns of fine wire 52, and the coil has the cross sectional configuration illustrated in Fig. 5. By placing this spool in a 'hole such as 32, see Fig. 6, with the land 50 at right angles to the length of the rail 38, there is provided a large quantity of straight wire between the arrows 54 and 56, on each side of the land or core 50, which is cutting the lines of flux in applicants trailing sustained field at right angles. Applicants trailing sustained field may be regarded as one in which the flux is moving through a magnetic core, see Figs. 7 and 8, through the portion of the rail just traversed by the core and thence emerging from the rail at varying angles depending upon the distance from the core vinto the air and back to the magnet. Viewed from above as in Fig. 8, it may be said that the flux is moving in vertical planes parallel to the length of the rail. This is not wholly true but generally true. It is evident, therefore, that in order to most squarely cut this flux, wires running transversely of the rail, as those between the arrows 54 and 56 of Fig. 6, will be most efifective. For the same reason wire which is running parallel to the length of the rail will be merely threading flux and not likely to indicate changes in flux direction or flux density. The pickup coil 42 here disclosed minimizes the amount of Wire that will be threading fiux in a trailing sustained field and increases the amount of wire that will be cutting such flux at right angles as compared with a coil having a circular vertical core with the wires circularly wound.

The leads from a coil of the type 42 are carried up suitably positioned channels 57 and 58. Applicants wind right-handed coils and left-handed coils. Each pair of openings such as 28, see Fig. 2, contains one right-hand and one left-hand Wound coil, and the lead holes 60, 62, 64 and 66 will always have similarly wound coils, that is, all right-hand wound or all left-hand wound. As stated, each pair of coils is connected to each other in series so that they will generate opposing signals due to vertical movements of the block and the lead of one coil is grounded as at 68 in Fig. 6 while the lead from the other coil is carried to a separate amplifier 70 which by conduotors 72 and 74 may actuate a pen unit such as 76.

Spools 42 are dropped into position in the block 10, the fit being snug and the wire connections may be made on the top of the block. Spools are easily replaced. For rail having a substantially narrower head, the applicants may provide a correspondingly narrower block with a similar arrangement of slightly smaller coils.

In moving this pickup block along the rail, applicants obtain excellent channel testing. The larger spools seated in the openings 34 and 66 were designed so that the edge of the spools at 78 and 80 would surely overlap the edges of the adjacent spools 82 and 84 because the side 86 of the rail 38 is the gauge side and most fissures start a little to the left of the median line 88 of the rail ball.

From the visual signal standpoint, a 39-foot rail being writen on two inches of tape 90, there will be no appreciable transverse difierence in the markings on the tape due to the fact that the signals received from the coil in the recess 34 will be slightly later than those received from the other three pairs of coils.

The single hole 36, Fig. 2, receives a coil spool 92 which is of the same type as that described in copending application Serial No. 72,382. Here a lower winding 94 is connected in series opposition to an upper winding 96, and one lead is grounded at 98, Fig. 6, and the other lead goes to the amplifier and thence to the pen unit 102, and the controls of this individual detector line are set so that when the coil 92 passes over a rail joint, a marking on the tape will be made comparable to that made by the other four pen units which respond to much more sensitive amplification. This means that this detection channel will not record even a large fissure. It records only breaks in the rail.

All of the coils have non-magnetic cores and, lengthwise of the rail, are mounted in touching engagement in order to keep the over-all length of each pair of coils as short as possible. A fissure fiux field in all longitudinal magnetic testing (as contrasted to the current system) has an appreciable length of approximately an inch, irrespective of the size of the fissure, but short of an actual break in the rail.

Having thus described our invention, what is claimed is:

A fissure detector assembly comprising a frame having a leading edge, a plurality of pairs ofsubstantially touching coils with vertical axes and non-magnetic cores mounted on said frame, the pairs of coils being in alignment parallel with the leading edge excepting for one pair disposed in touching engagement with adjacent pairs but therebehind, the coils of each pair being wound in series opposition and connected to a separate amplifier, and conductors leading the output of each amplifier to a separate pen unit forming part of a battery of pen units positioned over a single moving tape.

References Cited in the file of this patent UNITED STATES PATENTS Re. 18,555 Sperry Aug. 2, 1932 2,103,224 Schweitzer et a1. Dec. 21, 1937 2,109,455 Barnes et a1 Mar. 1, 1938 2,276,011 Billstein Mar. 10, 1942, 2,388,598 Cahill Nov. 6, 1945 2,388,683 Frickey et a1. Nov. 13, 1945 2,388,737 Gotha Nov. 13, 1945 

